1. Field of the Invention
The present invention generally relates to a printing control device that is operable in a color print mode, and more particularly to a printing control device that is appropriate for use in a digital complex system, such as a multi-function color printer or copier, which is provided with an automatic color sensing (ACS) ability and an interleaving print ability. Further, the present invention relates to an image processing apparatus in which the printing control device is provided.
2. Description of the Related Art
Generally, a color printing device is capable of switching from one of the color print mode and the black-and-white (B/W) print mode to the other. In the color print mode, the printing hardware uses all the four colors of cyan, magenta, yellow and black to print a color image. In the B/W (or monochrome) print mode, the printing hardware uses only black to print a black-and-white image. If the switching between the color print mode and the B/W print mode occurs frequently, the printing hardware is liable to reduction of the continuous printing speed and lowering of the device durability.
A conventional color printing device is provided with an automatic color sensing (ACS) ability. This printing device has a means for detecting color data contained in the printing data of a print request that is transmitted from a host computer to the printing device. With the ACS ability, the printing device is capable of automatically switching from one of the color print mode and the black-and-white (B/W) print mode to the other in response to the color sensing result.
A conventional digital complex system is provided with multiple image processing functions including the printer function, the fax function, the copier function and others, which are combined into a single system. The digital complex system usually has only one printing hardware, and the printing hardware must be shared by the multiple functions when executing a sequence of printing tasks by using the multiple functions.
To eliminate the problem, the conventional digital complex system has an interleaving print function. The interleaving print function is to arrange the printer, copier, fax and other application programs in the complex system such that sequential printing tasks occur in different application programs. With the interleaving print function, the complex system gives to the users such an impression as if the complex system can concurrently execute all the multiple functions. Actually, during execution of the interleaving printing function, one of the plurality of application programs is sequentially switched to another every time the printing of a predetermined number of images (or pages) for one of the sequential printing tasks on the printing hardware is finished.
In a digital complex system of the above type, the printing device (or the printing hardware) is provided with the ACS ability, and a problem arises when, in response to a received print request, the ACS function causes the switching between the color print mode and the B/W print mode to automatically occur during execution of the interleaving printing function. In other words, one of the plurality of application programs is sequentially switched to another every time the printing of the predetermined number of pages for one of the sequential printing tasks on the printing hardware is finished, and under such circumstances, the color/monochrome print mode switching is caused to occur for every timing of the application program switching. As the color/monochrome print mode switching will occur very frequently in such a case, the printing device of the above-mentioned digital complex system is more liable to reduction of the continuous printing speed and lowering of the device durability.